Information processing apparatus, method, and program

ABSTRACT

An information processing apparatus includes a control unit for controlling a color gamut conversion method that converts a color gamut of content data into a desired color gamut in accordance with the use of the content data; and a color gamut conversion unit for performing the color gamut conversion with respect to the content data by a method based on the control of the control unit.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. JP 2009-131257 filed in the Japanese Patent Office on May 29, 2009,the entire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information processing apparatus,method, and a program. In particular, the present invention relates toan information processing apparatus, method, and a program which make itpossible to appropriately perform color gamut conversion of contentdata.

2. Description of the Related Art

Recently, various kinds of digital image devices having different colorrepresentation areas have been increasing. As a method for coincidingcolors with each other between devices having different color gamuts tooutput the coincident colors, a workflow has been proposed on the basisof an sRGB (standard RGB) that is the standard color space for monitorsin the related art. However, with the appearance of many digital stillcameras and video cameras capable of capturing colors outside the sRGBcolor gamut, many methods for color gamut conversion (i.e.compression/decompression) have been proposed as methods of smoothlyoutputting captured wide color gamut image data to devices havingvarious color gamuts including wide color gamut displays and printerswith suppression of color inconsistency or high-luminance andhigh-saturation color bleeding.

As methods for color gamut conversion, for example, there are a methodhaving a complicated color gamut shape after conversion and a methodhaving a simplified color gamut shape after conversion.

A complicated color gamut has the same shape as the color gamut of, forexample, a print device such as a printer or the like. Generally, in thecase of the print device, the color forming method is complicated due tothe ink characteristics or the paper characteristics, and thus the shapeof the color gamut, which is the color range that the device canreproduce, also becomes complicated.

In contrast, a simplified color gamut has the same shape as the colorgamut of, for example, a display device such as an RGB monitor or thelike. Generally, in the case of the display device, the color forming isperformed by additive color mixing of light that RGB phosphors emit, andthus the shape of the color gamut, which is the color range that thedevice can reproduce, becomes simplified.

FIG. 1 is a diagram illustrating examples of compared shapes of variouskinds of color gamuts.

As illustrated in FIG. 1, in the case of an Adobe RGB color gamut 1 oran sRGB color gamut 2 for a display device, the shape of the color gamutis simplified, for example, as its external shape is roughly in the formof a straight line. In contrast, a printer color gamut 3 for a printdevice has a complicated shape, for example, in which its whole externalshape is roughly in the form of a curve.

Diverse methods for the color gamuts of images have been proposed, andmethods that correspond to the complicated shape have also been proposed(e.g. see Japanese Unexamined Patent Application Publication No.2000-278546 (corresponding to U.S. Pat. No. 6,437,792) and JapaneseUnexamined Patent Application Publication No. 2007-158948).

For example, in Japanese Unexamined Patent Application Publication No.2000-278546 (corresponding to U.S. Pat. No. 6,437,792), performing ofcolor gamut conversion so that the color difference in a uniform colorperception space is at a minimum by using a non-linear operation tocorrespond to even a complicated color gamut shape has been proposed.Also, for example, in Japanese Unexamined Patent Application PublicationNo. 2007-158948, a method of converting color gamut as preserving a grayaxis using 3DLUT has been proposed.

In contrast, methods that correspond to the simplified shape have alsobeen proposed (e.g. see Japanese Unexamined Patent ApplicationPublication No. 2007-142494 and Japanese Unexamined Patent ApplicationPublication No. 2003-244458). In Japanese Unexamined Patent ApplicationPublication No. 2007-142494, a method of performing color gamutcompression in a state where the space for performing the image processis kept RGB, almost linear operations are used and the color values arepreserved has been proposed. Also, in Japanese Unexamined PatentApplication Publication No. 2003-244458, a method of realizingsimplified color gamut compression which can maintain the grayscale andadjust a used compression table by hue as performing the process in astate where RGB is kept as the color space has been proposed.

Generally, in the case of the color gamut conversion that corresponds toeven the complicated color gamut shape, the load is large and a longoperation time is necessary. Accordingly, it is not suitable to thecolor gamut conversion of a moving image that necessitates real-time(i.e. instant) image output.

Also, in the case of the method corresponding to the simplified colorgamut shape, it is general that, although the load is small andhigh-speed operation is possible, the shape of the color gamut that canbe used is limited or adjustable parameters are greatly limited incomparison to the method corresponding to the high-definition colorgamut shape. Accordingly, unnatural appearance may occur depending uponthe light source for observing the image or the scene of an image.

Since the methods proposed as described above have diverse advantagesand defects, it is convenient if the color gamut conversion algorithmscan be selectively used according to their purposes.

In contrast, methods for selectively using color gamut conversionalgorithms have been proposed (e.g. Japanese Unexamined PatentApplication Publication Nos. 2002-218271, 2002-314828, and 2005-318491).For example, in Japanese Unexamined Patent Application Publication No.2002-218271, appropriate selection of one of a plurality of color gamutcompression methods according to the kind of input manuscript has beenproposed. In Japanese Unexamined Patent Application Publication No.2002-314828, changing of color gamut conversion methods in accordancewith the types of a plurality of subjects (e.g. natural images,graphics, texts, and the like) which exist together in one document hasbeen proposed. Further, in Japanese Unexamined Patent ApplicationPublication No. 2005-318491, a method of selecting one of pluralalgorithms (i.e. gamut mapping algorithms (GMA)) that perform colorgamut mapping using ICC profiles prescribed in ICC (International ColorConsortium) has been proposed.

Also, a method of dividing processing of a still image and a movingimage has been considered (e.g. see Japanese Unexamined PatentApplication Publication No. 2002-182634). In Japanese Unexamined PatentApplication Publication No. 2002-182634, a method of automaticallyswitching color reproduction methods according to differences between astill image and a moving image has been proposed.

SUMMARY OF THE INVENTION

However, in any one of Japanese Unexamined Patent ApplicationPublication Nos. 2002-218271, 2002-314828, and 2005-318491, the colorgamut conversion methods are just selected according to the kinds ofcontent data or the functions of devices, but the color gamut conversionmethods are not selected according to the use of content data. Also, asdescribed in Japanese Unexamined Patent Application Publication No.2002-182634, it is only possible to switch the color reproductionmethods in accordance with differences between a still image and amoving image.

Accordingly, the applied color gamut conversion method may not beappropriate, and may unnecessarily deteriorate the picture quality. Forexample, depending upon whether an image is to be printed on paper orthe like or to be displayed on a monitor, the necessary color gamutshape may differ. Accordingly, if the color gamut conversion method tobe adopted is determined merely by the kinds of content data, the colorgamut conversion may be performed in an inappropriate method, and thismay cause the occurrence of color blending or the unnecessary reductionof color representation, resulting in unnecessary deterioration ofpicture quality.

Recently, since most digital cameras, video cameras, portable phones,and the like, can capture both a still image and a moving image, andmany devices in which the above-described devices have been integrated,such as movie cameras, have appeared, it has been necessary that onedevice can process both still and moving images. That is, an appropriateuse of the diverse color gamut conversion methods is necessary.

In view of the above situation, it is desirable to realize moreappropriate color gamut conversion by using a plurality of color gamutconversion methods used for different purposes, for example, inaccordance with the use of target content data to be processed.

According to an embodiment of the present invention, there is providedan information processing apparatus including: a control means forcontrolling a color gamut conversion method that converts the colorgamut of content data into a desired color gamut in accordance with theuse of the content data; and a color gamut conversion means forperforming the color gamut conversion with respect to the content databy a method based on the control of the control means.

In the image processing apparatus according to an embodiment of thepresent invention, if the content data corresponds to a moving image,the control means selects an appropriate method according to the use ofa moving image, while if the content data corresponds to a still image,the control means selects an appropriate method according to the use ofa still image.

In the image processing apparatus according to an embodiment of thepresent invention, if the content data corresponds to a moving image,the color gamut conversion means performs a simplified shape color gamutconversion process that converts the color gamut of the content datainto a simplified shape color gamut with respect to the content data,while if the content data corresponds to a still image, the color gamutconversion means performs a complicated shape color gamut conversionprocess that converts the color gamut of the content data into acomplicated shape color gamut with respect to the content data.

In the image processing apparatus according to an embodiment of thepresent invention, if the content data corresponds to a still image, thecontrol means restricts the use of the content data by further using asub-condition, and if the content data satisfies the sub-condition, thecontrol means selects the appropriate method according to the use of amoving image, while if the content data does not satisfy thesub-condition, the control means selects the appropriate methodaccording to the use of a still image.

In the image processing apparatus according to an embodiment of thepresent invention, by the sub-condition, color gamut information can beadded to the content data when the content data is recorded.

The image processing apparatus according to an embodiment of the presentinvention further includes an image capturing means for capturing asubject and generating the content data, wherein the sub-conditioncorresponds to a mode in which the image capturing means generates thecontent data for image display.

The image processing apparatus according to an embodiment of the presentinvention further includes an image capturing means for capturing asubject and generating the content data, wherein the sub-conditioncorresponds to a continuous capturing mode in which the image capturingmeans continuously performs the capturing.

According to another embodiment of the present invention, there isprovided an information processing method including the steps of:controlling by the control means of an information processing apparatusa color gamut conversion method that converts the color gamut of contentdata into a desired color gamut in accordance with the use of thecontent data; and performing by color gamut conversion means of theinformation processing apparatus the color gamut conversion with respectto the content data by a method based on the control.

According to still another embodiment of the present invention, there isprovided a program prompting a computer to function as: a control meansfor controlling a color gamut conversion method that converts the colorgamut of content data into a desired color gamut in accordance with theuse of the content data; and a color gamut conversion means forperforming the color gamut conversion with respect to the content databy a method based on the control of the control means.

According to the embodiments of the present invention, the color gamutconversion method that converts the color gamut of the content data intothe desired color gamut is controlled in accordance with the use of thecontent data, and the color gamut conversion is performed with respectto the content data by the method based on the control.

As described above, according to the embodiments of the presentinvention, the information can be processed. In particular, the colorgamut conversion of the content data can be performed moreappropriately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating examples of compared shapes of variouskinds of color gamuts;

FIG. 2 is a diagram illustrating a configuration example of a videocamera to which the present invention is applied;

FIG. 3 is a flowchart illustrating an example of a flow of controlprocessing during recording;

FIG. 4 is a diagram illustrating a difference in feature between colorgamut conversion methods;

FIGS. 5A and 5B are diagrams illustrating an example of chromaticityinformation of an output color gamut;

FIGS. 6A and 6B are diagrams illustrating an example of a color gamut;

FIG. 7 is a diagram illustrating an example of a Cusp table;

FIG. 8 is a flowchart illustrating an example of a flow of complicatedshape color gamut conversion processing;

FIG. 9 is a diagram illustrating an example of shapes of color gamutconversion;

FIGS. 10A and 10B are diagrams illustrating an example of an LU table;

FIG. 11 is a diagram illustrating an example of a conversion function;

FIG. 12 is a diagram illustrating an example of a method of calculatingsaturation;

FIGS. 13A and 13B are diagrams illustrating comparison of a color gamutclip and a shape of color gamut conversion;

FIG. 14 is a diagram illustrating an example of a virtual clip boundary;

FIG. 15 is a diagram illustrating an example of a shape of coordinatemovement in an ideal color gamut conversion;

FIG. 16 is a diagram illustrating an example of a shape of a blend;

FIGS. 17A to 17C are diagrams illustrating a shape of mapping process inrespective directions;

FIG. 18 is a diagram illustrating an example of a difference betweenmapping directions;

FIG. 19 is a diagram illustrating an example of a blend function;

FIG. 20 is a diagram illustrating an example of a blend function;

FIG. 21 is a diagram illustrating an example of mapping;

FIGS. 22A and 22B are diagrams illustrating another example ofchromaticity information of an output color gamut;

FIG. 23 is a flowchart illustrating an example of a flow of a simplifiedshape color gamut conversion process;

FIGS. 24A to 24E are diagrams illustrating an example of a shape of modeconversion;

FIG. 25 is a diagram illustrating an example of a shape of Cuspinformation calculation;

FIG. 26 is a diagram illustrating an example of saturation calculationfor referring to compression function;

FIG. 27 is a diagram illustrating an example of a shape of virtual clipspace determination;

FIG. 28 is a flowchart illustrating another example of a flow of asimplified shape color gamut conversion processing;

FIG. 29 is a flowchart illustrating another example of a flow of controlprocessing during recording;

FIG. 30 is a diagram illustrating example sub-conditions; and

FIG. 31 is a block diagram illustrating a main configuration example ofa personal computer to which the present invention is applied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, best modes (hereinafter, referred to as embodiments) forcarrying out the present invention will be described. In addition, theexplanation will be made in the following order.

1. First embodiment (control processing during recording)

2. Second embodiment (complicated shape color gamut conversionprocessing)

3. Third embodiment (simplified shape color gamut conversion processing)

4. Fourth embodiment (simplified shape color gamut conversionprocessing)

5. Fifth embodiment (control processing during recording)

6. Sixth embodiment (personal computer)

1. First Embodiment

[Configuration of a Device]

FIG. 2 is a diagram illustrating a configuration example of a videocamera to which the present invention is applied. As illustrated in FIG.2, a video camera 101 captures a subject, generates image data of thesubject, and displays the image on a monitor 102 or records the imagedata on an optical disc 103 that is a recording medium.

The video camera 101 has both a moving image capture function and astill image capture function. That is, an image of image data generatedfrom the video camera 101 may be either of a moving image and a stillimage. Of course, the video camera 101 may be a digital still camerahaving a moving image capture function.

The video camera 101 has a system control unit 111, an input unit 112,an image capturing unit 113, an image processing unit 114, a displayunit 115, and a recording unit 116.

The system control unit 111 controls the respective units of the videocamera 101. The input unit 112, for example, is composed of switches,buttons, and the like, receives instructions input by a user (i.e. userinstruction), and provides the user instruction to the system controlunit 111. The system control unit 111 receives the user instruction, andcontrols the respective units according to the user instruction.

The image capturing unit 113 includes, for example, an optical systemsuch as a lens, an iris, and the like, and an image sensor such as a CCD(Charge Coupled Device) or CMOS (Complementary Metal OxideSemiconductor) sensor, captures a subject, generates image data of thesubject, and provides the image data to a color gamut conversion controlunit 121 of the image processing unit 114.

The image processing unit 114 performs image processing of the imagedata that is obtained from the image capturing unit 113. The imageprocessing unit 114 includes a color gamut conversion control unit 121,a simplified shape color gamut conversion processing unit 122, a buffer123, and a complicated shape color gamut conversion processing unit 124.

The color gamut conversion control unit 121 acquires the image dataobtained by the image capturing unit 113, select to perform color gamutconversion by using either of the simplified shape color gamutconversion processing unit 122 and the complicated shape color gamutconversion processing unit 124 in accordance with the use of the imagedata, and provides the image data to the selected unit.

However, if the complicated shape color gamut conversion processing unit124 is selected, the color gamut conversion control unit 121 simplyprovides the image data to the complicated shape color gamut conversionprocessing unit 124, and if necessary, provides the image data to thecomplicated shape color gamut conversion processing unit 124 after oncemaintaining the image data in a buffer 123.

For example, if the image data corresponds to a still image, itsmainstream use is printing, and in the case of displaying the image on amonitor, the picture quality demands from user become higher incomparison to the case of displaying a moving image. Accordingly, thecolor gamut conversion control unit 121 selects the complicated shapecolor gamut conversion processing unit 124.

In contrast, if the image data corresponds to a moving image, itsmainstream use is to display the image on the monitor. Also, since it isnecessary that the image display is performed in real time (i.e.instantly), a high-speed color gamut conversion is necessary. Further,even in the case of displaying the image on the monitor, the picturequality demands from users become lower than that in the case of a stillimage. Accordingly, the color gamut conversion control unit 121 selectsthe simplified shape color gamut conversion processing unit 122.

That is, the color gamut conversion control unit 121 determines thecolor gamut conversion method according to the use of the image datathat is estimated from the kind of the image data depending upon whetherthe image data is a moving image or a still image.

The simplified shape color gamut conversion processing unit 122 convertsthe color gamut of the provided image data into a simplified shape colorgamut. The simplified shape color gamut conversion processing unit 122provides the image data after the color gamut conversion to the displayunit 115 or the recording unit 116.

The complicated shape color gamut conversion processing unit 124converts the color gamut of the provided image data into a complicatedshape color gamut. The complicated shape color gamut conversionprocessing unit 124 provides the image data after the color gamutconversion to the display unit 115 or the recording unit 116.

The simplified shape color gamut conversion processing unit 122 canperform the color gamut conversion at higher speed than that of thecomplicated shape color gamut conversion processing unit 124. However,since the complicated shape color gamut conversion processing unit 124can perform the color gamut conversion of the image data into a morecomplicated shape color gamut than that converted by the simplifiedshape color gamut conversion processing unit 122, more accurate colorgamut conversion can be performed.

As described above, the simplified shape color gamut conversionprocessing unit 122 and the complicated shape color gamut conversionprocessing unit 124 perform the color gamut conversion of the image databy a method determined by the color gamut conversion control unit 121.

The display unit 115 displays the image of the provided image data onthe monitor 102. The recording unit 116 records the provided image dataon a recordable optical disc 103 mounted on the recording unit 116 (i.e.drive).

The monitor 102 may be a video camera dedicated monitor installed in ahousing of the video camera 101, or may be a general monitor, forexample, such as a television receiver.

The optical disc 103 is an example of a recording medium (storagemedium) that records the image data, and may be any one of the availablerecordable (i.e. additionally writable or correction-writable) media.For example, the optical disc may be may be a CD-R (CompactDisc-Recordable), CD-RW (Compact Disc-Rewritable), or the like. Forexample, the optical disc may be DVD±R (Digital VersatileDisc±Recordable) or DVD±RW (Digital Versatile Disc±Rewritable). Further,for example, the optical disc may be DVD-RAM (Digital VersatileDisc-Random Access Memory), BD-R (Blu-ray Disc-Recordable), BD-RE(Blu-ray Disc-Rewritable), or the like. If the optical disk correspondsto a recording device or a playback device, it may be even an opticaldisc (i.e. recording medium) outside these standards.

Also, instead of the optical disc 103, a flash memory, a hard disc, or atape device may be used. Further, the optical disc 103 may not be aportable removable medium, and may be a built-in recording medium. Ofcourse, the recording medium may be configured as a separate body fromthe video camera 101, for example, such as a peripheral device, aserver, or the like.

In this case, the color gamut conversion is a process that changes therange of the color gamut. Accordingly, the color gamut conversionincludes both the narrowing of the color gamut and the widening of thecolor gamut. For example, it includes the narrowing of the color gamutin a certain portion and the widening of the color gamut in anotherportion. Generally, the most color gamut conversions may be color gamutcompression that narrows the color gamut. Accordingly, hereinafter, thecolor gamut compression will be basically exemplified. However, thefollowing description can also be basically applied to the color gamutexpansion that widens the color gamut.

In this case, as shown in FIG. 2, the video camera 101 may be an exampleof a recording device. The recording device may be a device except forthe video camera, and may be any function device that performs the colorgamut conversion. For example, the recording device may be aninformation processing device which acquires image data from the outsideand performs image processing such as color gamut conversion processingor the like.

[Flow of Processing]

The video camera 101 as configured above performs appropriate colorgamut conversion in accordance with the use of the image data byperforming control process during recording when it outputs the imagedata obtained from the image capturing unit 113 to the monitor 102 orthe optical disc 103.

With reference to the flowchart of FIG. 3, an example of a flow ofcontrol processing during recording will be described.

If the control processing during recording starts, the color gamutconversion control unit 121 determines whether the image data providedfrom the image capturing unit 113 is image data for recording that is tobe recorded on the optical disc 103 on the basis of a user designationreceived by the input unit 112, a capturing mode of the image capturingunit 113, or the like, in step S101. If it is determined that the imagedata is the image data for recording of a moving image or a still image,the processing proceeds to step S102.

In step S102, the color gamut conversion control unit 121 determineswhether the image data is a moving image. If it is determined that theimage data is a moving image, the processing proceeds to step S103.

That is, the image data in this case is the image data for recording ofa moving image. In this case, the image data is recorded on the opticaldisc 103, and a moving image is displayed on the monitor 102.Accordingly, the video camera 101 necessitates a real-time (i.e.instant) output of the image data. That is, it is necessary to performthe color gamut conversion process at high speed. Also, since the imagedata is a moving image, it is considered that the image data recorded onthe optical disc 103 is mainly to be displayed on the monitor or thelike. Further, since the image data is a moving image, the demand forthe picture quality is relatively low.

From the foregoing, it is preferable to adopt the color gamut conversionby the simplified shape color gamut conversion processing unit 122 thatcan perform the color gamut conversion of the image data into asimplified shape color gamut which is close to the shape of the colorgamut of the monitor at high speed. Accordingly, in this case, the colorgamut conversion control unit 121 selects the simplified shape colorgamut conversion processing unit 122, and provides the image data or thelike to the simplified shape color gamut conversion processing unit 122.

In step S103, the simplified shape color gamut conversion processingunit 122 converts the color gamut of the image data into a simplifiedshape color gamut by performing the simplified shape color, gamutconversion process with respect to the provided image data. In stepS104, the display unit 115 displays the image of the image data afterthe color gamut conversion on the monitor 102. Also, in step S105, therecording unit 116 records the image data after the color gamutconversion on the optical disc 103, and ends the control process duringrecording.

Also, in step S102, if it is determined that the image data is not amoving image, the processing proceeds to step S106.

That is, the image data in this case is the image data for recording ofa still image. In this case, the image data is only recorded on theoptical disc 103. In this case, the color gamut conversion process maybe performed at low speed. However, since the image data is a stillimage, it is considered that the image data recorded on the optical disc103 is mainly to be printed by a printer or the like. Further, since theimage data is a still image, the demand for the picture quality isrelatively high.

From the foregoing, it is preferable to adopt the color gamut conversionby the complicated shape color gamut conversion processing unit 124 thatcan perform the color gamut conversion of the image data into acomplicated shape color gamut which is close to the shape of the colorgamut of the printer or the like. Accordingly, in this case, the colorgamut conversion control unit 121 selects the complicated shape colorgamut conversion processing unit 124, and provides the image data or thelike to the complicated shape color gamut conversion processing unit124.

In step S106, the complicated shape color gamut conversion processingunit 124 converts the color gamut of the image data into a complicatedshape color gamut by performing the complicated shape color gamutconversion process with respect to the provided image data. In stepS107, the recording unit 116 records the image data after the colorgamut conversion on the optical disc 103, and then ends the controlprocess during recording.

Also, in step S101, if it is determined that the image data is not theimage data for recording, the processing proceeds to step S108.

That is, the image data in this case is not the image data forrecording, but is the image data of a monitor image (i.e. moving image).The monitor image is a moving image displayed on the monitor 102 forconfirmation before the capturing is performed. That is, the image ofthe image data in this case is displayed on the monitor 102.Accordingly, it is necessary to perform the color gamut conversionprocess at high speed. Further, since the image data is a moving imageand is for confirming the picture, the demand for the picture quality islow. Also, the image data has typically no use except for the display onthe monitor 102.

From the foregoing, it is preferable to adopt the color gamut conversionby the simplified shape color gamut conversion processing unit 122 thatcan perform the color gamut conversion of the image data into asimplified shape color gamut which is close to the shape of the colorgamut of the monitor 102 at high speed. Accordingly, in this case, thecolor gamut conversion control unit 121 selects the simplified shapecolor gamut conversion processing unit 122, and provides the image dataor the like to the simplified shape color gamut conversion processingunit 122.

In step S108, the simplified shape color gamut conversion processingunit 122 converts the color gamut of the image data into a simplifiedshape color gamut by performing the simplified shape color gamutconversion process with respect to the provided image data. In stepS109, the display unit 115 displays the image of the image data afterthe color gamut conversion on the monitor 102, and then end the controlprocess during recording.

As described above, the video camera 101 can control the color gamutconversion method in accordance with the use of the image data, andperform the color gamut conversion more appropriately.

Here, an explanation of the complicated shape color gamut conversion andthe simplified shape color gamut conversion will be made. In general,the color gamut of the image data during capturing is sufficiently largeto be the equivalent of limitless. Accordingly, since the color that isexpressed through the playback device or the output device in thepost-end process may be destroyed, the input device predicts the colorgamut of the output device to some extent, and performs the processingof the color of the image data so that the processed color enters intothe color gamut, i.e. the color gamut conversion.

FIG. 4 is a diagram illustrating the difference in feature between thecolor gamut conversion methods. As illustrated in FIG. 4, the simplifiedshape color gamut conversion and the complicated shape color gamutconversion have different features.

For example, in the case of the simplified shape color gamut conversion,the image data can be color-gamut-converted only into the standard RGBcolor gamut (i.e. restricted color gamut) such as sRGB or the like, butin the case of the complicated shape color gamut conversion, the imagedata can be converted into diverse shape color gamuts.

Also, the processing speed of the simplified shape color gamutconversion side is higher than the processing speed of the complicatedshape color gamut conversion side, and thus a moving image can becolor-gamut-converted in real time (i.e. instantly). In contrast, thecomplicated shape color gamut conversion has a long delay time, and thusit is assumed that the complicated shape color gamut conversion isperformed by so called offline processing using a buffer 123.

Also, the number of control parameters of the simplified shape colorgamut conversion is smaller than the number of control parameters of thecomplicated shape color gamut conversion. In other words, a largernumber of parameters are used for the complicated shape color gamutconversion, and thus more diverse controls can be performed through thecomplicated shape color gamut conversion.

Further, the memory capacity necessary for the simplified shape colorgamut conversion is smaller than the memory capacity necessary for thecomplicated shape color gamut conversion. In the same manner, the numberof used operations of the simplified shape color gamut conversion issmaller than the number of used operations of the complicated shapecolor gamut conversion. In other words, the complicated shape colorgamut conversion necessitates a larger amount of used data or operationsthan that is necessary in the simplified shape color gamut conversion,and thus the processing is complicated with large load.

Also, in the case of the simplified shape color gamut conversion, thecolor space (i.e. the color space to be converted) used for the colorgamut conversion is a space, for example, which corresponds to the RGBor in which the RGB can be converted into a simplified color conversion,while in the case of the complicated shape color gamut conversion, thecolor space is CIELAB, CIELUV, or a perceptibly equal color space basedon the same.

As described above, it is frequent that the target color gamut of thesimplified shape color gamut conversion basically becomes the standardcolor gamut that can be expressed in most devices, i.e. the same colorgamut as sRGB. The color gamut that can be expressed in most devicessuch as sRGB is generally narrow, and this may cause even the color thatcan be expressed by an output device to be converted. This risk becomesa tradeoff for expressing the color gamut at high speed withoutdestroying the color.

In contrast, the target color gamut of the complicated shape color gamutconversion is not limited to the color gamut of the standard RGB system.For example, if the output device has already been known at a time pointwhere the image data is captured, the color gamut information of thedevice is obtained in advance, and a high-precision color gamutconversion is performed, so that, for example, even the color gamuthaving the complicated shape such as the printing device can beconverted.

Also, once the color gamut of the image data has been converted intosRGB, the color may be restricted when it is output through a devicehaving a wide color gamut such as a wide color gamut TV or the like.Even in the case of using a simplified shape color gamut compressionalgorithm in order to avoid such risk, it is possible to convert thecolor gamut of the image data into the color gamut of a wide color gamutTV if the color gamut of the image data is converted into the standardRGB color gamut (e.g., Adobe RGB, wide RGB, bg-RGB, sc-RGB, or the like)that is somewhat wider than the sRGB or if the color gamut informationof a wide color gamut TV having a high use frequency is known in advanceby a user designation or the like.

As described above, by estimating the use of the image data that isobtained through capturing of a subject depending upon whether the imagedata is a moving image or a still image and changing the color gamutconversion algorithm according to the use, the video camera 101 canappropriately select and use the simplified shape color gamut conversionand the complicated shape color gamut conversion, and thus problemsoccurring due to the use of only one kind of color gamut conversionmethod can be suppressed.

As described above, although it is exemplified that the video camera 101is provided with two color gamut conversion processing units which arethe simplified shape color gamut conversion processing unit 122 and thecomplicated shape color gamut conversion processing unit 124, the numberof color gamut conversion processing units is optional, and three ormore color gamut conversion processing units may be provided. In thiscase, the color gamut conversion control unit 121 may select one ofthree or more color gamut conversion methods.

Also, the video camera 101 may be provided with one or more color gamutconversion processing units in which the color gamut conversion methodcan be changed by a control parameter or the like under the control ofthe color gamut conversion control unit 121. That is, for example, thesimplified shape color gamut conversion processing unit 122 and thecomplicated shape color gamut conversion processing unit 124 may beintegrally configured.

In this case, for example, the color gamut conversion control unit 121designates the color gamut conversion method or sets values of controlparameters and the like in accordance with the use of the image data(i.e. content data), and the color gamut conversion processing unitperforms the color gamut conversion in a method based on the control.

2. Second Embodiment

[Complicated Shape Color Gamut Conversion Processing]

Next, details of the complicated shape color gamut conversion processingwill be described. By the complicated shape color gamut conversionprocessing, the color gamut of the image data is converted into anoutput color gamut (i.e. output RGB) of the chromaticity information asillustrated in FIGS. 5A and 5B.

Now, it is assumed that a user has designated still image capturingthrough the input unit 112 and the instruction has reached respectiveunits through the system control unit 111. The color gamut conversioncontrol unit 121 selects the complicated shape color gamut conversionprocessing unit 124, and provides the image data obtained from the imagecapturing unit 113 to the complicated shape color gamut conversionprocessing unit 124.

The complicated shape color gamut compression method that is performedin the embodiment of the present invention will be described.

As illustrated in FIG. 6A, in the case where the color gamut of acertain device is expressed in a YCC (Y, Cb, Cr) space (i.e. color gamut201), a plane obtained by cutting a equal-saturation plane, asillustrated in FIG. 6B, can be expressed as a two-dimensional YC planehaving a vertical axis that represents luminance (Y) and a horizontalaxis that represents saturation (C) (i.e. color gamut 202). The colorgamut shape on this plane can approximate to a triangle that connects awhite point, a black point, and the maximum saturation point Cusp asshown as the color gamut 202 indicated in FIG. 6B if CY coordinates ofthe maximum saturation point Cusp is known. By maintaining CYcoordinates (i.e. Cusp information) of Cusp points on severalrepresentative hue surfaces H as a numeral table using this property,the color gamut 201 of the device can be approximately defined. Thetable of CY coordinates (Cusp information) of the maximum saturationpoints Cusp of the representative hues is called a Cusp table.

FIG. 7 is a diagram illustrating an example of the Cusp table. The graph211-1 shows the luminance Y of the Cusp point for the hue H. The graph211-2 shows the saturation C of the Cusp point for the hue H. Also, thetable 212 shows values of luminance Y and saturation C of therepresentative hue H. Since the luminance or the saturation between therepresentative hue values (i.e. intermediate hue values) can be easilyobtained by performing interpolation process using values of the table212, the graph 211-1, the graph 211-2, and the table 212 are roughlyequivalent information. As described above, in the Cusp table, the CYcoordinates of the Cusp points are indicated for at least therepresentative saturation, and its format is optional.

The complicated shape color gamut conversion processing unit 124performs the color gamut conversion (compression or decompression) usingthe above-described Cusp table. Hereinafter, the details of the colorgamut conversion process will be described.

Referring to the flowchart of FIG. 8, an example of a flow of acomplicated shape color gamut conversion process will be described. Ifnecessary, explanation will be made with reference to FIGS. 9 to 15.

If the complicated shape color gamut conversion process starts, thecomplicated shape color gamut conversion processing unit 124 performsconversion of RGB data (Ri, Gi, Bi) of a processed pixel into YCC data(Yi, Cbi, Cri) that is luminance and color difference data by performingcalculation, for example, as shown in Equation (1) below so that colorblending does not occur due to the color gamut conversion in step S201.

$\begin{matrix}{\begin{pmatrix}{Yi} \\{Cbi} \\{Cri}\end{pmatrix} = {\begin{pmatrix}0.2990 & 0.5870 & 0.1140 \\{- 0.1687} & {- 0.3313} & 0.5000 \\0.5000 & {- 0.4187} & {- 0.0813}\end{pmatrix} \cdot \begin{pmatrix}{Ri} \\{Gi} \\{Bi}\end{pmatrix}}} & (1)\end{matrix}$

Then, the complicated shape color gamut conversion processing unit 124converts the format of the processed pixel from YCC (Yi, Cbi, Cri) toYCH (Yi, Ci, Hi) (i.e. converts the coordinate system from YCCcoordinates into YCH coordinates) by performing calculation, forexample, a shown in Equations (2) to (4) below in step S202.

$\begin{matrix}{{Yi} = {Yi}} & (2) \\{{Ci} = \sqrt{{Cbi}^{2} + {Cri}^{2}}} & (3) \\\left\{ \begin{matrix}{{{if}\mspace{14mu}{Cri}} > 0} \\{\mspace{14mu}{{Hi} = {{\arctan\left( \frac{Cri}{Cbi} \right)} \cdot \frac{180}{\pi}}}} \\{else} \\{\mspace{14mu}{{Hi} = {{{\arctan\left( \frac{Cri}{Cbi} \right)} \cdot \frac{180}{\pi}} + 360}}}\end{matrix} \right. & (4)\end{matrix}$

If the format is converted, the complicated shape color gamut conversionprocessing unit 124 calculates CY coordinate information (Ccp, Ycp) ofthe maximum saturation point (Cusp point) of the respective hues Hi ofthe target color gamut in step S203. In this case, since the targetcolor gamut has been determined at a time point where the color gamutconversion processing starts (i.e. also has the color gamutinformation), the CY coordinate information of the Cusp point can beobtained from the information of the target color gamut (e.g. YCC data).

In step S204, the complicated shape color gamut conversion processingunit 124 designates the non-mapping boundary and a mapping limitboundary.

FIG. 9 is a diagram illustrating an example of shapes of color gamutconversion. In FIG. 9, an area surrounded by a thick line (i.e. an areasurrounded by a triangle having a white point, a black point, and Cusppoint as its apexes) is a final target compressed area, that is, atarget color gamut. A T-boundary (Target boundary) 221 is a border (i.e.boundary) except for Y-axis of the target area. A boundary that issomewhat small in saturation direction on the basis of the T-boundary221 is a non-mapping boundary (i.e. U-boundary (Uncompressed boundary))222. An area surrounded by the Y-axis and the U-boundary 222 is thenon-mapping area, and pixels included therein are notcolor-gamut-converted (coordinate-moved). Next, it is necessary todesignate to what extent the area is converted into the targetcompressed area. A boundary for designating the extent to which thecolor gamut of the color of the image content data is spread is anL-boundary (mapping Limit boundary) 223. In the color gamut conversion,the L-boundary 223 becomes the boundary that is expanded in thesaturation direction from the T-boundary 221. That is, the color gamutconversion means the conversion of the area surrounded by the U-boundary222 and the L-boundary 223 into an area surrounded by the U-boundary 222and the T-boundary 221.

In indicating the color gamut conversion only in the saturationdirection, a0 _(in) of FIG. 9 is coordinate-moved, for example, to a0_(out) by the color gamut conversion. In this case, colors of saturationhigher than that of the L-boundary 223 are all clipped to the T-boundary221 (i.e. are all coordinate-moved onto the T-boundary 221). Forexample, a1 _(in) of FIG. 9 is coordinate-moved to a1 _(out).

FIGS. 10A and 10B are diagrams illustrating an example of an LU table.The LU table 231 as illustrated in FIG. 10B is table information thatindicates the saturation of the designated non-mapping boundary (i.e.U-boundary 222) and the mapping limit boundary (i.e. L-boundary 223) forrespective hue at the rate based on the T-boundary 221 (i.e. saturationrate). If colors indicated by points correspond to high-saturation colordistribution existing in the world as illustrated in FIG. 10A in thecase where it is difficult to limit the color gamut of an image beforethe color gamut conversion, such as an image captured by a digital stillcamera, a video camera, or the like, the LU table 231 as illustrated inFIG. 10B can be obtained by setting the L-boundary to be somewhat largercentering around a portion that projects from the color gamut of an RGBspace that is indicated as a hexagon and determining the U-boundary sideaccording to the rule of U-boundary=1.0−((L-boundary−1.0)/2). In FIGS.10A and 10B, although the whole hue is set at a constant saturation rateof the L-boundary to the U-boundary (e.g. the L-boundary is set to 1.5and the U-boundary is set to 0.75), these values may be changed forrespective hue.

The determination of the saturation rate of the L-boundary to theU-boundary is optional. For example, the complicated shape color gamutconversion processing unit 124 may maintain in advance the LU table 231as illustrated in FIGS. 10A and 10B, or the LU table may be acquiredfrom the outside.

Referring again to FIG. 8, the complicated shape color gamut conversionprocessing unit 124 defines a conversion function in step S205.

For example, if the shape of the color gamut conversion when Hi=150° inFIGS. 10A and 10B is indicated as a function, it becomes a curve 241 asillustrated in FIG. 11. In this case, the saturation rate of theU-boundary 222 is 0.75 and the saturation rate of the L-boundary 223 is1.5. This curve 241 is called a conversion function (or a mappingfunction). The range in which the slope is 1 represents the non-mappingarea. The color gamut conversion indicates the compression of the rangesurrounded by the U-boundary 222 and the L-boundary 223 of thehorizontal axis into the range surrounded by the U-boundary 222 and theT-boundary 221 of the vertical axis. At this time, the conversion methodis optional, and diverse methods may be considered. For example, thesolid line 241A means a linear compression. The dashed line 241B is anexample obtained by performing gradual compression through smoothbending of the function. The dashed dotted line 241C means a color gamutclip in the T-boundary 221 rather than the compression.

That is, along the shape of the curve 241 in this range, for example, asshown in FIG. 9, the ratio (r:s) of the distance up to the T-boundary221 to the distance up to the U-boundary 222 of a0 _(out), which is themovement place of a0 _(in) of which the ratio of the distance up to theL-boundary 223 to the distance up to the U-boundary 222 is p:q as shownin FIG. 9, is determined. In other words, the function (i.e. conversionfunction) indicated by the curve 241 in FIG. 11 indicates thecompression rate R_ccomp in the saturation direction of any pixel to beprocessed, and a virtual clip boundary of the pixel to be processed isdetermined by the output values of the function.

The mapping function is determined depending upon the values of theL-boundary 223 and the U-boundary 222, and if the values of theL-boundary 223 and the U-boundary 222 are changed for respective hues,the mapping function is also changed.

Referring again to FIG. 8, the complicated shape color gamut conversionprocessing unit 124 determines the virtual clip boundary in step S206.

The complicated shape color gamut conversion processing unit 124 refersto the defined conversion function in the processing in step S205 usingthe saturation Ci of the pixel to be processed. However, since theconversion function has a value obtained by normalizing the saturationin the T-boundary 221 to “1”, it is necessary to obtain the saturationCi_c in the T-boundary 221 of the luminance such as the pixel to beprocessed. If it is assumed that the CY coordinates of the pixel to beprocessed (the pixel subject to processing) are (Ci, Yi), the saturationCi_c in the T-boundary 221 of the luminance which is the same as that inthe pixel to be processed, for example, as illustrated in FIG. 12, canbe obtained as the saturation of the cross point of the straight linethat connects the white point and Cusp point and the straight line thatconnects the pixel (Ci, Yi) to be processed and the luminance point (0,Yi) of the pixel to be processed on the Y-axis.

Using the saturation Ci_c at the cross point Ci_c and the saturation Ciof the pixel to be processed, the saturation Ci_norm for referring tothe conversion functions can be calculated using Equation (5) below.

$\begin{matrix}{{Ci\_ norm} = \frac{Ci}{Ci\_ c}} & (5)\end{matrix}$

For example, the complicated shape color gamut conversion processingunit 124 determines the saturation direction compression rate R_ccomp ofthe pixel to be processed using the saturation Ci_norm with reference tothe conversion function indicated by the curve 241 of FIG. 11. Once theR_ccomp is determined, a virtual clip boundary (V-boundary) of the pixelto be processed can be determined. By determining the V-boundary asdescribed above, the color gamut conversion may be considered as aprocess of repeatedly performing the color clip for the virtual clipboundary.

FIGS. 13A and 13B are diagrams illustrating comparison of a color gamutclip and the shape of color gamut conversion. FIG. 13A is a diagramillustrating the shape of the color gamut clip. The color gamut clip, asshown in FIG. 13A, indicates the movement of a color of the outside ofthe target color gamut onto the T-boundary 221 that is the boundary ofthe target color gamut (i.e. clipped to the T-boundary 221). Forexample, as shown in FIG. 13A, the pixel to be processed, which isindicated as a white circle, is coordinate-moved to the clip point onthe T-boundary 221, which is indicated as the black circle.

FIG. 13B is a diagram illustrating the shape of the color gamutconversion. As described above, the color gamut conversion is themovement of the pixel to be processed onto the virtual clip boundarythat corresponds to the pixel to be processed. For example, as shown inFIG. 13B, the pixel to be processed 251 is coordinate-moved to the clippoint 252 on the V-boundary 261A, and the pixel to be processed 253 iscoordinate-moved to the clip point 254 on the V-boundary 261B. That is,the color gamut conversion may be considered to be equivalent to theperforming of the same process as the case of the color gamut clip ofFIG. 13A for the respective pixels to be processed.

For example, in explaining the Cusp point, the CY coordinates (Ccp_V,Ycp) of the clip points Cusp_V of the Cusp point of the CY coordinates(Ccp, Ycp) can be calculated as in Equation (6) below using thesaturation direction compression rate R_ccomp.Cusp_(—) V=(Ccp _(—) V, Ycp)=(R _(—) ccomp×Ccp, Ycp)  (6)

From the CY coordinates of the clip point Cusp_V, the virtual clipboundary (V-boundary) 261 is determined. For example, the virtual clipboundary (V-boundary) 261 of the Cusp point, as illustrated in FIG. 14,is composed of a line segment having the clip point Cusp_V and the whitepoint as its both ends, and a line segment having the clip point Cusp_Vand the black point as its both ends.

That is, the V-boundary 261 is determined by the above-describedconversion function and the ratio (p:q) of the distance up to theL-boundary 223 of the pixel to be processed to the distance up to theU-boundary 222. In other words, the pixels to be processed, which havethe same ratio (p:q) of the distance up to the L-boundary 223 to thedistance up to the U-boundary 222, share the V-boundary 261.

Once the Cusp_V is determined, the virtual clip color gamut can bedetermined. After this process, the pixel to be processed is made to mapon the virtual clip boundary (V-boundary) as illustrated in FIG. 15.

Here, an ideal mapping direction is considered. Although diverse ways ofthinking may exist with respect to the mapping direction, a mappingdirection that realizes a natural appearance, for example, asillustrated in FIG. 15, is clipped to a direction in which colorsdisappear through compression of the saturation in the case where theluminance of the pixel to be processed is close to the white point orthe black point, while in the case of the luminance neighboring theCusp_V, the compression in a direction in which the colors remain, whichis not compression simply in the saturation direction, but is thecompression which moves somewhat in the luminance direction, isperformed.

In order to realize the ideal clip direction, the complicated shapecolor gamut conversion processing unit 124, for example, as illustratedin FIG. 16, defines at least two kinds of fixed mapping directions. Oneof the fixed mapping directions corresponds to the mapping (A direction)which erases colors that compress only in the saturation direction, andthe other of the fixed mapping directions corresponds to the mapping (Bdirection) which leaves colors that move in both the saturationdirection and the luminance direction. The final mapping direction isdetermined by blending the two directions in an appropriate ratio. In anexample of FIG. 16, the A and B directions are blended in the ratio of1:2. That is, if it is possible to appropriately define the blend ratioin the fixed mapping directions for the respective pixels to beprocessed, the ideal mapping direction as illustrated in FIG. 15 can berealized. This is realized using a blend function to be described later.

The fixed mapping directions may be considered in diverse ways ofthinking, and three kinds of representative mapping directions areexemplified. First is a C-direction mapping as illustrated in FIG. 17A.The C-direction mapping corresponds to a mapping direction forperforming compression in the saturation direction. Second is a Cuspdirection mapping as illustrated in FIG. 17B. The Cusp direction mappingcorresponds to a mapping direction for performing compression withrespect to the luminance point of Cusp on the Y-axis (luminance)directions. Third is a BW direction mapping as illustrated in FIG. 17C.The BW direction mapping corresponds to a mapping direction forperforming compression toward the black point if the pixel to beprocessed is brighter than the luminance of the Cusp, while itcorresponds to a mapping direction for performing compression toward thewhite point if the pixel to be processed is darker than the luminance ofthe Cusp. Hereinafter, with reference to FIG. 18, a method ofcalculating mapping points in respective directions will be described.Here, the CY coordinates of the pixel to be processed (Ci, Yi), thewhite point (0, 1), the black point (0, 0), and the Cusp (Ccp, Ycp) areall known.

Referring again to FIG. 8, the complicated shape color gamut conversionprocessing unit 124 performs calculation of the C-direction mappingpoint Pc in step S207.

The point Pc is obtained as the cross point of the straight line thatconnects the pixel to be processed and the luminance point (0, Yi) ofthe pixel to be processed on Y-axis and the straight line that connectsthe white point and the Cusp. The C-direction mapping is a mapping forerasing the colors.

In step S208, the complicated shape color gamut conversion processingunit 124 performs the calculation of the BW-direction mapping point Pbw.

The point Pbw is obtained as the cross point of the straight line thatconnects the pixel to be processed and the black point and the straightline that connects the white point and the Cusp. The BW-directionmapping is a mapping for remaining the colors.

In step S209, the complicated shape color gamut conversion processingunit 124 performs calculation of the Cusp-direction mapping point Pcp.

The point Pcp is obtained as the cross point of the straight line thatconnects the pixel to be processed and the luminance point (0, Ycp) ofthe Cusp on the Y-axis and the straight line that connects the whitepoint and the Cusp. The Cusp-direction mapping is a mapping for somewhatremaining the colors.

In step S210, the complicated shape color gamut conversion processingunit 124 performs the calculation of the final mapping point Pout.

By blending at least two of three fixed direction mapping pointscalculated as shown in FIG. 18 in an appropriate ratio, the complicatedshape color gamut conversion processing unit 124 realizes the idealcompression clip direction points as illustrated in FIG. 15. Asdescribed above, the C-direction mapping point is a clip point in adirection for erasing the colors, the BW-direction mapping point is aclip point that leaves the colors, and the Cusp-direction mapping pointis an intermediate clip point.

FIG. 19 is a diagram illustrating an example of a blend function thatrealizes the ideal compression clip direction points by blending theC-direction mapping point and the BW-direction mapping point. In thecase where the luminance in areas A (as indicated by both-side arrows301 and 302) of FIG. 19 is in the neighborhood of the white point andthe black point, the use rate of the C-direction mapping point asillustrated as a curve 304 is heightened, and in the case where theluminance is in an area B (as indicated as both-side arrow 303) of FIG.19 is in the neighborhood of the Cusp, the use rate of the BW-directionmapping point as illustrated as a curve 305 is heightened. The blendfunctions (as indicated as curves 304 and 305) of FIG. 19, asillustrated in FIG. 19, may blend two mapping directions, or may blendthree mapping directions (including the Cusp-direction mapping). As aresult, it is preferable to define the blending functions so that themapping directions as illustrated in FIG. 15 can be realized.

Two kinds of actual blend functions, which define only the BW-directionuse rate, are prepared as indicated in the intermediate portion 312 ofFIG. 20. One is a function of the processed pixel on the side that isbrighter than that of the Cusp, and the other is a function of theprocessed pixel on the side that is darker than that of the Cusp. Thehorizontal axis represents luminance in which the luminance of the Cuspand the white point and the luminance of the Cusp and the black pointare normalized into 0.0 and 1.0, respectively. In this case, theC-direction user rate can be obtained by subtracting the BW-directionuse rate from 1.0.

Since the luminance and the saturation of the Cusp point of the colorgamut greatly differ according to the hue as illustrated as a curve 351of the graph in the upper portion of FIG. 21, the shape of the colorgamut is also changed accordingly (see color gamuts 361A to 367A in theintermediate portion of FIG. 21). Accordingly, it is preferable that theblend functions are also changed according to the hues, and by definingthe functions as in the intermediate portion 312 of FIG. 20, thecomplicated shape color gamut conversion processing unit 124 canappropriately change the blend functions for the respective hues inaccordance with the luminance positions of the Cusp points of the hues.For example, the shapes of the blend functions in somewhat high hue Aand hue B in a state where the luminance at the Cusp point is somewhatlow are shown in the upper portion 311 and the lower portion 313 of FIG.20. It can be confirmed that the blend function is changed according tothe luminance at the Cusp point. If the blend function is changed asdescribed above, as illustrated in the intermediate portion of FIG. 21,ideal mapping directions as shown in FIG. 18 e.g. the direction forerasing the color in the neighborhood of the white point and the blackpoint and the direction for remaining the color in the neighborhood ofthe Cusp point as shown as the color gamuts 362B to 367B in the lowerportion of FIG. 21, can be realized even though the color gamut shapesare changed for the respective hues.

Referring again to FIG. 8, in step S210, the complicated shape colorgamut conversion processing unit 124 performs the calculation of thefinal mapping point Pout.

The BW-direction use rate that is obtained with reference to the blendfunction using the luminance Yi of the processed pixel is calledUseR_BW. The final mapping point Pout (Co, Yo) can be obtained byEquations (7) and (8) below using the C-direction mapping point (Cc, Yc)and the BW-direction mapping point (Cbw, Ybw).Yo=UseR _(—) BW·Ybw+(1.0−UseR _(—) BW)·Yc  (7)Co=UseR _(—) BW·Cbw+(1.0−UseR _(—) BW)·Cc  (8)

In step S211, the complicated shape color gamut conversion processingunit 124 converts the format of the output content data. If it isassumed that the CY coordinates of the final mapping point obtained bythe processing in step S210 are (Co, Yo), the complicated shape colorgamut conversion processing unit 124 calculates the YCC coordinates Pout(Yo, Cbo, Cro) of the final mapping point by performing conversion fromthe YCH coordinate system into the YCC coordinate system as expressed inEquations (9) to (11) below.Since Ho=HiYo=Yo  (9)Cbo=Co·cos(Ho)  (10)Cro=Co·sin(Ho)  (11)

Further, in step S212, the complicated shape color gamut conversionprocessing unit 124 converts the YCC data into the final output RGB data(Ro, Go, Bo) as in Equation (12) below.

$\begin{matrix}{\begin{pmatrix}{Ro} \\{Go} \\{Bo}\end{pmatrix} = {\begin{pmatrix}1.0000 & 0.0000 & 1.4020 \\1.0000 & {- 0.3441} & {- 0.7141} \\1.0000 & 1.7720 & 0.0000\end{pmatrix} \cdot \begin{pmatrix}{Yo} \\{Cbo} \\{Cro}\end{pmatrix}}} & (12)\end{matrix}$

Once the RGB coordinates of the final mapping point are calculated, thecolor gamut conversion processing is ended.

Of course, as the above-described complicated shape color gamutcompression algorithm, for example, an algorithm except for theabove-described algorithm may be adopted. For example, the operationequations may be executed using high-precision three-dimensional LUT(3DLUT). In the case of using the 3DLUT, it is also possible to performthe color gamut compression in consideration of the user taste, such asnon-display of the compression method as operation or the like. Also, inthe above-described method, it is exemplified that the color gamut shapecan be expressed in the Cusp table. However, by using the 3DLUT, anycolor gamut shape can be expressed.

3. Third Embodiment

[Simplified Shape Color Gamut Conversion Processing]

Next, details of the simplified shape color gamut conversion processingwill be described. Now, it is assumed that a user has designated movingimage capturing through the input unit 112 and the instruction hasreached respective units through the system control unit 111. The colorgamut conversion control unit 121 selects the simplified shape colorgamut conversion processing unit 122, and provides the image dataobtained from the image capturing unit 113 to the simplified shape colorgamut conversion processing unit 122.

The simplified shape color gamut conversion method that is performed inthe embodiment of the present invention will be described. In this case,as illustrated in FIGS. 22A and 22B, it is assumed that the output colorgamut corresponds to an sRGB space.

With reference to the flowchart of FIG. 23, an example of a flow of thesimplified shape color gamut conversion processing will be described. Itis assumed that the processed input RGB data is (Ri, Gi, Bi), and theoutput RGB data is (Ro, Go, Bo). In the case of the complicated shapecolor gamut conversion, the color gamut conversion is performed afterthe input RGB data is converted into YCH data that represents luminance,saturation, and hue. In contrast, in the case of the simplified shapecolor gamut conversion, the color gamut conversion is performed afterthe input RGB data is converted into YMM data that represents luminance,maximum value of RGB, and minimum value of RGB. Accordingly, it ispossible to obtain the luminance of the Cusp without referring to theCusp table that represents the color gamuts, and thus the reduction ofthe use amount of memory, the simplification of the operationprocessing, and the reduction of the load can be achieved.

Once the simplified shape color gamut conversion processing starts, instep S401, the simplified shape color gamut conversion processing unit122, in order to seek for the simplification of the operationprocessing, calculates the data (i.e. YMM data) having the luminance,the maximum value of the RGB data, and the minimum value of the RGB data(Yi, Maxi, Mini) from the RGB data (Ri, Gi, Bi) of the processed pixelusing Equations (13) to (15) below.Yi=0.299×Ri+0.587×Gi+0.114×Bi  (13)Maxi=max(Ri,Gi,Bi)  (14)Mini=min(Ri,Gi,Bi)  (15)

Also, it is stored which component of RGB has the maximum value or theminimum value. For example, the order of variables that are calledRGBOrder is recorded in the form as in Equation (16).RGBOrder=(3,1,2)  (16)

The numerals on the right side of Equation (16) indicate the order ofred, green, and blue colors, starting from the left, “1” means theminimum value, “2” means the intermediate value, and “3” means themaximum value.

Instep S402, the simplified shape color gamut conversion processing unit122 calculates information of the maximum saturation point Cusp of thecolor gamut in the hue of the processed pixel (Yi, Maxi, Mini). In orderto perform this calculation, here, some geometrical properties in theYCC space of the RGB space will be confirmed.

If the RGB space is converted into the YCC space, the non-saturationaxis 401 of the RGB space as illustrated in FIG. 24A becomes Y-axis ofthe YCC space as illustrated in FIG. 24B. Accordingly, in the YCC spaceas illustrated in FIG. 24B, the RGB coordinates on the Y-axis becomeR=G=B, and the YMM coordinates become Y=Max=Min.

Next, the RGB coordinates of the maximum saturation point Cusp on theYCC space in the respective saturations are confirmed. The RGBcoordinates for 6 representative colors (R, Y, G, C, B, M) are as shownin a table as illustrated in FIG. 24C, and the shape of the change bythe saturation of the Cusp becomes the shape of curves 404 to 406 asillustrated in FIG. 24D.

From them, it can be confirmed that any one among the RGB coordinates ofthe Cusp is surely “1” and “0”. Accordingly, as illustrated in FIG. 24E,it can be known that the YMM coordinates of the Cusp are (Ycp, 1, 0) ifthe Y coordinate is set to Ycp. Further, the YMM coordinates on the line407 that connects the white point and the Cusp point are confirmed.Since the YMM coordinates of the white point is (1, 1, 1) and the YMMcoordinates of the Cusp point is (Ycp, 1, 0), it can be known that themaximum value of the color point on the straight line 407 that connectsthe white point and the Cusp point is “1”.

As described above, using the confirmed geometrical properties, theunclear information, i.e. Ycp, is obtained from the YMM coordinates ofthe Cusp. As illustrated in FIG. 25, if it is assumed that the processedpixel is Pi (Yi, Maxi, Mini), the minimum coordinates of the color pointwhich has the luminance Yi that is the same as Pi, and which is on theline that connects the white point and the Cusp point is called α. If αis known, it is the similar figure of ΔF and ΔG as illustrated in FIG.25, and thus the Ycp can be calculated by Equation (17) below.

$\begin{matrix}{{{{From}\mspace{14mu}\left( {1 - {Ycp}} \right)\text{:}\mspace{11mu}\left( {1 - {Yi}} \right)} = {1\text{:}\mspace{11mu}\left( {1 - \alpha} \right)}}{{Ycp} = \frac{{Yi} - \alpha}{1 - \alpha}}} & (17)\end{matrix}$

At this time, as illustrated in FIG. 25, the ratio w can be calculatedby Equation (18) below.

$\begin{matrix}{w = \frac{1 - {Yi}}{{{Max}\; i} - {Yi}}} & (18)\end{matrix}$

Accordingly, α in Equation (17) can be calculated by Equation (19) belowusing the ratio w.α−Yi=(Mini−Yi)×w∴α=(Mini−Yi)×w+Yi  (19)

By arrangement through substitution of Equation (19) in Equation (17),the Ycp can be finally calculated from Equation (20) below using the YMMcoordinates (Yi, Maxi, Mini) of the processed pixel.

$\begin{matrix}{{Ycp} = \frac{{Yi} - {{Min}\; i}}{{{Max}\; i} - {{Min}\; i}}} & (20)\end{matrix}$

Accordingly, using this method, the simplified shape color gamutconversion processing unit 122 can calculate the Cusp information (i.e.YMM coordinates of the Cusp) only by knowledge of the YMM coordinates ofthe processed pixel without referring to the color gamut information,and determine the color gamut necessary for color gamut compression ofthe processed pixel.

The simplified shape color gamut conversion processing unit 122 performsdesignation of the non-mapping boundary (U-boundary) and the mappinglimit boundary (L-boundary) in step S403.

In the same manner as the complicated shape color gamut conversion, theLU table 231 as illustrated in FIG. 10B may be referred to. However, inorder to promote the speed increases and simplification of theprocessing in the simplified shape color gamut conversion, theL-boundary is set to 1.5 and the U-boundary is set to 0.75 withoutfollowing the hue. Accordingly, the simplified shape color gamutconversion processing unit 122 can set the L-boundary and the U-boundaryonly by referring to integers (i.e. it becomes unnecessary to refer tothe LU table for the respective hues).

In step S404, the simplified shape color gamut conversion processingunit 122 performs the definition of the conversion function. The methodof referring to the conversion function (e.g. see FIG. 11) is the sameas that in the complicated shape color gamut conversion. However, it ispossible to study the reduction of the number of constituent data of theconversion function.

In step S405, the simplified shape color gamut conversion unit 122determines the virtual clip space. The simplified shape color gamutconversion processing unit 122 refers to the conversion function usingthe YMM coordinates of the processed pixel. Since the conversionfunction has a value Ci_norm obtained by normalizing the saturation inthe T-boundary to “1”, as shown in FIG. 26, the value Ci_norm can beobtained from Equation (21) below in the simplified shape color gamutconversion.

$\begin{matrix}{{Ci\_ norm} = \frac{{{Max}\; i} - {Yi}}{1.0 - {Yi}}} & (21)\end{matrix}$

The simplified shape color gamut conversion processing unit 122determines the saturation-direction compression rate R_ccomp of theprocessed pixel, for example, by referring to the conversion function asillustrated in FIG. 11 using the value Ci_norm. The simplified shapecolor gamut conversion processing unit 122, in the same manner as thecomplicated shape color gamut conversion, can realize the color gamutconversion by determining the virtual clip color gamut for eachprocessed pixel and repeating the clip processing as illustrated inFIGS. 13A and 13B using the compression rate R_ccomp.

The shape of the clip processing is shown in FIG. 27. the YMMcoordinates of the Cusp point are (Ycp, 1, 0), and the YMM coordinatesof the color point (Cusp″) on the Y-axis having the same luminance asthe luminance of the Cusp point are (Ycp, Ycp, Ycp). The maximum valueof the YMM coordinates is linearly increased in directions from theY-axis to the Cusp point and from Ycp to “1”. Also, the minimum value islinearly decreased in a direction from Ycp to “0”. Accordingly, if it isassumed that the compression rate from the T-boundary 421 is R_ccomp,the YMM coordinates of the Cusp_V located between them can be calculatedby Equation (22) below.YMM Coordinates (Ycp,Maxcpv,Mincpv) of Cusp_(—) V=(Ycp,R _(—)ccomp×(1−Ycp),(1−R _(—) ccomp)×Ycp))  (22)

Once the Cusp_V is determined, the simplified shape color gamutconversion processing unit 122, as illustrated in FIG. 27, can determinethe virtual clip space from the V-boundary 461, and thus can perform themapping process on the color gamut.

In step S406, the simplified shape color gamut conversion processingunit 122 obtains the C-direction mapping point Pc (see FIG. 17A) thatindicates the saturation C-direction mapping process. The C-directionmapping point Pc can be obtained as the cross point of the straight linethat connects the processed pixel and the luminance point (Yi, Yi, Yi)of the processed pixel on the Y-axis and the straight line that connectsthe white point and the Cusp point. The C-direction mapping is a mappingfor erasing the colors.

In step S407, the simplified shape color gamut conversion processingunit 122 obtains the BW-direction mapping point Pbw (see FIG. 17B) thatindicates the mapping place in the BW direction. The BW-directionmapping point Pbw can be obtained as the cross point of the straightline that connects the processed pixel and the black point and thestraight line that connects the white point and the Cusp point. TheBW-direction mapping is a mapping for remaining the colors.

In step S408, the simplified shape color gamut conversion processingunit 122 obtains the Cusp-direction mapping point Pcp that indicates themapping place in the Cusp direction. The Cusp-direction mapping pointPcp can be obtained as the cross point of the straight line thatconnects the processed pixel and the luminance point (Ycp, Ycp, Ycp) ofthe Cusp point on the Y-axis and the straight line that connects thewhite point and the Cusp point. The Cusp-direction mapping is a mappingfor remaining the colors.

In step S409, the simplified shape color gamut conversion processingunit 122 calculates the final mapping point Pout by blending therespective mapping points obtained in the respective processes in stepsS406 to S408 according to the blend function.

For example, it is assumed that the BW-direction use rate obtained withreference to the blend function as illustrated in FIG. 19 or 20 usingthe luminance Yi of the processed pixel is UseR_BW. By using theC-direction mapping point Pc (Yc, Maxc, Minc) and the BW-directionmapping point Pbw (Ybw, Maxbw, Minbw), the final mapping point Pout (Yo,Maxo, Mino) can be obtained as in Equations (23) to (25) below.Yo=UseR _(—) BW·Ybw+(1.0−UseR _(—) BW)·Yc  (23)Maxo=UseR _(—) BW·Maxbw+(1.0−UseR _(—) BW)·Maxc  (24)Mino=UseR _(—) BW·Minbw+(1.0−UseR _(—) BW)·Minc  (25)

In step S410, the simplified shape color gamut conversion processingunit 122 first determines two colors among Ro, Go, and Bo using RGBOrderthat is the information which is preserved when the input RGB data isconverted into the YMM data in the process in step S401 and whichindicates which color of RGB has the maximum value or the minimum value.In this case, from the Equation (16), the maximum value is R and theminimum value is G. Accordingly, Ro and Go can be obtained by Equations(26) and (27) below.Ro=Maxo  (26)Go=Mino  (27)

The remaining Bo can be obtained using Equation (28) below from theluminance generation equation.

$\begin{matrix}{{Yo} = {{{{0.299 \times {Ro}} + {0.587 \times {Go}} + {0.114 \times {Bo}}}\therefore{Bo}} = \frac{{Yo} - {0.299 \times {Ro}} - {0.587 \times {Go}}}{0.114}}} & (28)\end{matrix}$

Once the final output RGB data is calculated, the simplified shape colorgamut conversion processing is ended.

As described above, the simplified shape color gamut conversionprocessing unit 122 can perform the color gamut conversion easier thanthe complicated shape color gamut conversion processing.

4. Fourth Embodiment

[Simplified Shape Color Gamut Conversion Processing 2]

The simplified shape color gamut conversion processing algorithm may beone other than the above-described algorithms, or for example, may befurther simplified. Another example of the flow of the simplified shapecolor gamut conversion processing will be described with reference tothe flowchart of FIG. 28.

In FIG. 28, the simplified shape color gamut conversion processing unit122 performs the respective processes in steps S501 and S502 in the samemanner as those in steps S401 and S402 of FIG. 23.

However, in FIG. 28, the simplified shape color gamut conversionprocessing unit 122 performs clip processing as shown as a solid line241A in FIG. 11 without compressing the color gamut. Accordingly, theprocesses corresponding to the steps S403 to S405 are omitted, and themapping process is performed.

The simplified shape color gamut conversion processing unit 122 performsthe respective processes in steps S503 and S504 in the same manner asthe processes in the step S406 and S407 in FIG. 23.

However, in FIG. 28, the blending mapping directions are limited to twodirections. Accordingly, the process corresponding to the step S408 isomitted.

In step S505, the simplified shape color gamut conversion processingunit 122 obtains the final mapping point Pout by blending theC-direction mapping point Pc obtained by the processing in step S503 andthe BW-direction mapping point Pbw obtained by the processing in stepS504.

In step S506, the simplified shape color gamut conversion processingunit 122 calculates the final output RGB data (Ro, Go, Bo) in the samemanner as the step S410 of FIG. 23, and end the simplified shape colorgamut conversion processing.

By doing this, the simplified shape color gamut conversion processingunit 122 can further simplify the color gamut conversion processing, andthus can realize the reduction of the processing time and the load.Accordingly, the real-time processing performance can be heightened.

5. Fifth Embodiment

[Control Processing 2 During Recording]

The control processing during recording may be performed using analgorithm except for the above-described algorithm with reference to theflowchart of FIG. 3. For example, the color gamut conversion processingduring recording may be selected using another condition.

With reference to the flowchart of FIG. 29, another example of the flowof the control processing will be described.

Even in this case, the respective units of the video camera 101 performthe control processing during recording in the same manner as thecontrol processing as described above with reference to the flowchart ofFIG. 3.

However, if it is determined that the image data is a still image instep S602, the color gamut conversion control unit 121 determineswhether a sub-condition is satisfied in step S606. The sub-condition isto further limit the use of the image data. If it is determined that thesub-condition is satisfied, the processing returns to the step S603, andthe image data is converted by the simplified shape color gamutconversion processing. Also, if it is determined that the sub-conditionis not satisfied in the step S606, the processing proceeds to step S607,and the image data is converted by the complicated shape color gamutconversion processing.

That is, if the sub-condition is satisfied even though the image data isa still image, the color gamut conversion control unit 121 controls toperform the simplified shape color gamut conversion of the image data inthe same manner as the case in which the image data is a moving image,and control to perform the complicated shape color gamut conversion ofonly the still image that does not satisfy the sub-condition.

The sub-condition may be any one that limits the use of the image data,and an example thereof is shown in FIG. 30.

For example, the sub-condition may be “the color gamut information canbe recorded together with the image data”.

In this case, the color gamut information may be considered in diversemanners, and as the existing one, the annexed color gamut informationusing the ICC profile may be the color gamut information recorded in aheader of Exif (Exchangeable Image File Format). If the annexing of thecolor gamut information is possible during recording, in the inputdevice, it is not necessary to perform the color gamut compression inthe final output device, and the color gamut information may be annexedto the RGB color gamut, which has been compressed as an appropriatestandard RGB color gamut (that may be the standard RGB color gamutsomewhat wider than the sRGB). Accordingly, the color gamut conversioncontrol unit 121 controls to perform the simplified shape color gamutconversion.

Also, for example, the sub-condition may be “it is assumed that thecapturing mode is accurately to be used in a display device”.

For example, if the still image capturing mode is on the assumption thatthe display device is accurately considered as the output device, suchas “web content data capturing mode”, “capturing mode for transmissionto a portable phone”, “capturing mode for viewing photo frames”, and thelike, the compression place color gamut is limited to the RGB colorgamut. Accordingly, the color gamut conversion control unit 121 controlsto perform the simplified shape color gamut conversion of the image datain order to convert the color gamut into an appropriate RGB color gamut.

In this case, as the compression place RGB color gamut, for example, itis considered that the sRGB is effective. In this case, the use of awide color gamut display in portable phones or photo frames has recentlybeen increasing, and if such a display becomes the object of processing,restoration meta information that includes information necessary torestore the color gamut before color gamut conversion may be annexedtogether with color gamut information of the compressed standard RGBcolor gamut, and the display device may be made to appropriately executethe restoration process or color gamut conversion.

Further, for example, the sub-condition may be “the capturing mode is acontinuous capturing mode”.

If the still image capturing mode is a continuous capturing mode, speedis necessitated, and the color gamut conversion control unit 121controls to perform the simplified color gamut conversion of the imagedata that has a high processing speed. Further, the conversion placecolor gamut may be fixed to the standard RGB system (e.g. sRGB or thelike), and the density of processing may be limited.

As described above, if the image data is a still image, the video camera101 selects the color gamut conversion processing further using thesub-condition, and thus unnecessarily heavy processing is not performedto achieve an efficient color gamut conversion operation.

6. Sixth Embodiment

[Personal Computer]

The above-described series of processing may be performed by hardware orby software. In this case, for example, a personal computer asillustrated in FIG. 31 may be configured.

In FIG. 31, a CPU (Central Processing Unit) 701 of a personal computer700 executes various kinds of processing according to a program storedin a ROM (Read Only Memory) 702 or a program loaded from a storage unit713 to a RAM (Random Access Memory) 703. In the RAM 703, data necessaryfor the CPU 701 to execute various kinds of processing is appropriatelystored.

The CPU 701, the ROM 702, and the RAM 703 are connected together througha bus 704. To this bus 704, an input/output interface 710 is alsoconnected.

To the input/output interface 710, an input unit 711 composed of akeyboard, a mouse, and the like, a display composed of a CRT (CathodeRay Tube), an LCD (Liquid Crystal Display), or the like, an output unit712 composed of a speaker or the like, a storage unit 713 composed of ahard disc or the like, and a communication unit 714 composed of a modemor the like are connected. The communication unit 714 performscommunication process through a network including the Internet.

To the input/output interface 710, if necessary, a drive 715 isconnected, and removable media 721 such as a magnetic disc, an opticaldisc, an optomagnetic disc, a semiconductor memory, or the like, isappropriately mounted, and a computer program read from them isinstalled in the storage unit 713 if necessary.

In the case of executing the above-described series of processing bysoftware, a program configuring the software is installed from a networkor a recording medium.

The recording medium, for example, separately from a device main body asillustrated in FIG. 31, may be configured not only by a removable media721 composed of a magnetic disc (including a flexible disc) recordedwith a program distributed to transmit a program to a user, an opticaldisc (including a CD-ROM (Compact Disc-Read Only Memory) and a DVD(Digital Versatile Disc)), an optimagnetic disc (including MD (MiniDisc)), a semiconductor memory, or the like, but also by a ROM 702recorded with a program which is pre-inserted into the device main bodyto be transferred to a user, a hard disc included in the storage unit713, or the like.

In this case, a program executed by a computer may be a program thatperforms processing in a time-series manner according to the order asdescribed above in the specification or may be a program that performsprocessing in parallel or separately when such processing is necessary.

In addition, in this specification, the steps describing the programrecorded on the recording medium include processes performed in atime-series manner according to the order as described above andprocesses performed in parallel or separately even though it is notnecessarily performed in a time-series manner.

Also, in this specification, the system indicates the whole deviceconfigured by a plurality of devices.

Also, as described above, the configuration explained as one device (ora processing unit) may be divided into a plurality of devices (orprocessing units). In contrast, as described above, a plurality ofdevices (or processing units) may be gathered and configured as onedevice (or a processing unit). Also, it is also possible to add aconfiguration in addition to the above-described devices (or processingunits). Further, if the configuration or operation is substantially thesame as the whole system, a part of the configuration of a certaindevice (or a processing unit) may be included in the configuration ofanother device (or another processing unit). The present invention isnot limited to the above-described embodiments, and diversemodifications can be made without departing from the scope of theinvention.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An information processing apparatus comprising: acontrol unit operable to control a color gamut conversion method thatconverts a color gamut of content data into a first color gamut inaccordance with use of the content data, wherein if the content datacorresponds to a moving image, the control unit selects a firstconversion method according to use of the moving image, while if thecontent data corresponds to a still image, the control unit selects asecond conversion method according to use of the still image, wherein ifthe content data corresponds to the still image, the control unitrestricts the use of the content data by further using a sub-condition,and if the content data satisfies the sub-condition, the control unitselects the first conversion method according to the use of the movingimage, while if the content data does not satisfy the sub-condition, thecontrol unit selects the second conversion method according to the useof the still image; and a color gamut conversion unit operable toperform the color gamut conversion with respect to the content data bythe selected one of: the first conversion method and the secondconversion method based on control of the control unit.
 2. Theinformation processing apparatus according to claim 1, wherein if thecontent data corresponds to the moving image, the color gamut conversionunit performs a first shape color gamut conversion process that convertsthe color gamut of the content data into a first shape color gamut withrespect to the content data, while if the content data corresponds tothe still image, the color gamut conversion unit performs a second shapecolor gamut conversion process that converts the color gamut of thecontent data into a second shape color gamut with respect to the contentdata.
 3. The information processing apparatus according to claim 1,wherein the sub-condition is capability to add color gamut informationto the content data when the content data is recorded.
 4. Theinformation processing apparatus according to claim 1, furthercomprising an image capturing unit operable to capture a subject andgenerate the content data, wherein the sub-condition corresponds to amode in which the image capturing unit generates the content data forimage display.
 5. The information processing apparatus according toclaim 1, further comprising an image capturing unit operable to capturea subject and generating the content data, wherein the sub-conditioncorresponds to a continuous capturing mode in which the image capturingunit continuously performs capturing.
 6. An information processingmethod comprising: controlling by a control unit of an informationprocessing apparatus a color gamut conversion method that converts acolor gamut of content data into one of a first color gamut or a secondcolor gamut in accordance with use of the content data, wherein if thecontent data corresponds to a moving image, the control unit selects afirst conversion method according to a use of the moving image, andwherein if the content data corresponds to a still image, the controlunit determines whether the content data satisfies a sub-condition,wherein if the content data satisfies the sub-condition, the controlunit selects the first conversion method, and wherein if the contentdata does not satisfy the sub-condition, the control unit selects asecond conversion method according to a use of the still image; andperforming by a color gamut conversion unit of the informationprocessing apparatus, the color gamut conversion with respect to thecontent data, by the selected one of: the first conversion method andthe second conversion method based on control of the control unit. 7.The information processing method according to claim 6, wherein thesub-condition is capability to add color gamut information to thecontent data when the content data is recorded.
 8. The informationprocessing method according to claim 6, wherein the sub-conditioncorresponds to a mode in which an image capturing unit generates thecontent data for image display.
 9. The information processing methodaccording to claim 6, wherein the sub-condition corresponds to acontinuous capturing mode in which an image capturing unit continuouslyperforms capturing.
 10. A non-transitory computer-readable storagemedium having stored thereon, a computer program having at least onecode section for information processing, the at least one code sectionbeing executable by a computer for causing the computer to perform stepscomprising: controlling a color gamut conversion method that converts acolor gamut of content data into one of a first color gamut or a secondcolor gamut in accordance with use of the content data, wherein if thecontent data corresponds to a moving image, selecting a first conversionmethod according to a use of the moving image, and wherein if thecontent data corresponds to a still image, determining whether thecontent data satisfies a sub-condition, wherein if the content datasatisfies the sub-condition, selecting the first conversion method, andwherein if the content data does not satisfy the sub-condition,selecting a second conversion method according to a use of the stillimage; and performing the color gamut conversion with respect to thecontent data by the selected one of: the first conversion method and thesecond conversion method based on the control of the control unit. 11.The computer-readable storage medium according to claim 10, wherein thesub-condition is capability to add color gamut information to thecontent data when the content data is recorded.
 12. Thecomputer-readable storage medium according to claim 10, wherein thesub-condition corresponds to a mode in which an image capturing unitgenerates the content data for image display.
 13. The computer-readablestorage medium according to claim 10, wherein the sub-conditioncorresponds to a continuous capturing mode in which an image capturingunit continuously performs capturing.